1. Field of the Invention
The present invention relates to a low-noise signal amplifying circuit and method thereof, and more particularly to a low-noise amplifier having low noise-figure and low return loss and the related method.
2. Description of the Prior Art
In a wireless communication system, the LNA provides the first level of amplification of the RF signal received at the system's antenna. Therefore, the main function of the LNA is to amplify the extremely low RF signals without adding noise, thus preserving the required signal-to-noise ratio (SNR) of the system at extremely low power levels. Moreover, when the LNA is arranged to receive the RF signal, the impedances between the input terminal of the LNA and the previous circuit stage should be matched to reduce the return loss of the RF signal. Accordingly, the LNA design presents considerable challenge due to its simultaneous requirement for high gain, low noise figure, good input and output matching and unconditional stability at the lowest possible current draw from the LNA. Proper LNA design is crucial in today's communication solutions. Due to the complexity of the signals in modern digital communications, additional design considerations need to be addressed during a LNA design procedure.